Ralphy, But we design to the worst cases expected. First we decide what type of fire we'll have-low, moderate, severe. and then chose hazard. From the we chose an area of acceptable loss, choose a density that will under normal conditions based on that first choice contain a fire to no more than that area, and then determine the hardest place(s) within the building for meeting the criterion we just established. These areas are the most demanding and we calculate systems to them. Fires elsewhere will be of the same nature but getting the water there will be less demanding. Or fires may be contained well before we've met maximum and they those will be less demanding no matter where they are. I love folks trying to create magnitudes of precision from variable s of reality. Kinda like the silk purse/sow's ear thing.
On Thu, Sep 24, 2009 at 10:46 AM, Ralphy Henderson <[email protected]> wrote: > You're right but that's not the point. The point is maybe the particular > design area is not indicative of the whole building's situation. Maybe the > most demanding area could be looped at the branchlines then a supplemental > calc performed on the next most demanding area which would establish the norm > for the rest of the building. Since most of the time your most demanding area > is going to be the one, not neccessarily farthest from the riser but the one > with the most sprinklers in your design area or the higher occupancy > classification which may not be the case for the typical areas of the > building. A secondary calc could establish that but the primary could be > calc'd for it's specific characteristics. > > > --- On Thu, 9/24/09, Timothy W Goins <[email protected]> wrote: > > > From: Timothy W Goins <[email protected]> > Subject: RE: Inadequate Water > To: [email protected] > Date: Thursday, September 24, 2009, 4:26 PM > > > "maybe looping a few of the branchlines in the most demanding area would > solve things" I always thought that the remote area calcs and design set the > standard/minimum for the entire system. No one knows, but GOD and an > arsonist, where the actual remote area might be or fire may start/be. > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Ralphy > Henderson > Sent: Thursday, September 24, 2009 11:10 AM > To: [email protected] > Subject: RE: Inadequate Water > > > Isn't an issue of 5 psi really a non issue? I mean, you generally have an > AHJ mandated safety factor (or should) of 5-10%, a hose allowance that may > or may not be used, plus calculations that are based upon Hazen-Williams > which in itself is not as accurate as other methods and provides an > additional safety margin. > Not only that but there are usually design options as well. Perhaps the > remote area could be re-evaluated - maybe there's that head in the closet > that really doesn't need to be included in the calcs, maybe looping a few of > the branchlines in the most demanding area would solve things, changing BFP > to a more friendly friction loss model, did the hydraulics program use the > modified equivalent lengths based upon NFPA #13 or were these considerably > rounded up by default (I've seen that)? Could changing sprinklers to larger > / smaller orifice help, sliding up and down the design density curve to meet > actual calculated sq. ft'g (if no reductions are taken) etc.. Even without > consideration of the above it would seem that 5 psi is not lawsuit material > - at least to me. As long as this is not storage or extra hazard I don't see > what the big deal is. -Ralphy > > > > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > > > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > -- Ron Greenman Instructor Fire Protection Engineering Bates Technical College Tacoma, WA Member: SFPE, ASCET, NFPA, AFSA, NFSA AFAA, WSAFM _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
